A transmitting apparatus includes an OFDM modulator that generates a first modulation symbol by modulating a first information signal using a first modulation scheme, a signal point of the first modulated information signal being at a first position in an in-phase quadrature-phase plane. A second modulation symbol by modulating a second information signal using the first modulation scheme, and by changing a second position at which a signal point of the modulated second information signal is arranged to a third position in the in-phase quadrature-phase plane, and an OFDM modulation signal including the first modulation symbol and the second modulation symbol, wherein the OFDM modulation signal comprises a plurality of subcarriers.
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1. A transmitting apparatus comprising: an OFDM modulator that generates a first modulation symbol by modulating a first information signal using a first modulation scheme, a signal point of the first modulated information signal being arranged at a first position in an in-phase quadrature-phase plane, a second modulation symbol by modulating a second information signal using the first modulation scheme, and by changing a second position at which a signal point of the modulated second information signal is arranged to a third position in the in-phase quadrature-phase plane, wherein the third position is different from the first position, an OFDM modulation signal including the first modulation symbol and the second modulation symbol, wherein the OFDM modulation signal comprises a plurality of subcarriers; and a transmitter that transmits the OFDM modulation signal.
A transmitting device uses OFDM (Orthogonal Frequency-Division Multiplexing) to send data. It modulates a first data signal using a specific modulation method (e.g., QAM) and maps the resulting symbol to a first point on an IQ (In-phase Quadrature) plane. It then modulates a second data signal using the same modulation method, but deliberately shifts the symbol's position on the IQ plane from where it normally would be to a different location. These two modified symbols are included in an OFDM signal containing multiple subcarriers, which the device then transmits. The key is intentionally moving the second symbol's position in the IQ plane to distinguish it.
2. The transmitting apparatus according to claim 1 , wherein the first modulation symbol and the second modulation symbol are arranged in a same subcarrier in the OFDM modulation signal.
The transmitting device as described above transmits the first and second modulated symbols within the *same* subcarrier of the OFDM signal. Instead of distributing them across different frequencies, they are multiplexed together on a single frequency channel within the OFDM structure. This allows transmitting both signals simultaneously using the same frequency.
3. A transmission method comprising: generating a first modulation symbol by modulating a first information signal using a first modulation scheme, a signal point of the first modulated information signal being arranged at a first position in an in-phase quadrature-phase plane; generating a second modulation symbol by modulating a second information signal using the first modulation scheme, and by changing a second position at which a signal point of the second modulated information signal is arranged to a third position in the in-phase quadrature-phase plane, wherein the third position is different from the first position, and generating an OFDM modulation signal including the first modulation symbol and the second modulation symbol, wherein the OFDM modulation signal comprises a plurality of subcarriers; and transmitting the OFDM modulation signal.
A method for transmitting data involves modulating a first data signal using a particular modulation scheme (e.g., QAM) and placing the resulting symbol at a specific location on an IQ plane. A second data signal is modulated using the same scheme, but its symbol's location on the IQ plane is changed from its original position to a different location. Both symbols are incorporated into an OFDM signal that includes several subcarriers. Finally, the OFDM signal is transmitted. The important distinction is that the second symbol's position is intentionally shifted on the IQ plane.
4. The reception method according to claim 3 , wherein the first modulation symbol and the second modulation symbol are arranged in a same subcarrier in the OFDM modulation signal.
The transmission method detailed above includes arranging both the first and second modulated symbols within a shared subcarrier of the OFDM signal. This means they are transmitted concurrently on the same frequency channel within the OFDM framework.
5. A reception apparatus comprising: a receptor that receives an OFDM modulation signal to which a first modulation symbol and a second modulation symbol are multiplexed, wherein the OFDM modulation signal comprises a plurality of subcarriers, the plurality of subcarriers include the first modulation symbol arranged in a first position in an in-phase quadrature-phase plane, and the second modulation symbol arranged in a third position in the in-phase quadrature-phase plane, the first modulation symbol is a symbol to which a first information signal is modulated using a first modulation scheme, the second modulation symbol is a symbol obtained by modulating a second information signal using the first modulation scheme, and by changing a second position at which a signal point of the second modulated information signal is arranged to the third position in the in-phase quadrature-phase plane; and a demodulator that separates the first modulation symbol and the second modulation symbol included in the OFDM signal, demodulates the first information signal from the first modulation symbol, and demodulates the second information signal from the second modulation symbol.
A receiving device receives an OFDM signal containing multiple subcarriers. This signal contains two multiplexed symbols: a first symbol and a second symbol. The first symbol, representing a first data signal modulated with a certain scheme, is positioned at a specific location on the IQ plane. The second symbol, derived from a second modulated data signal (using the same scheme) has its position on the IQ plane shifted to a different location. The receiver then separates these two symbols, demodulates the first data signal from the first symbol, and demodulates the second data signal from the second symbol based on the shifted location.
6. The reception apparatus according to claim 5 , wherein the first modulation symbol and the second modulation symbol are arranged in a same subcarrier in the received OFDM modulation signal.
The receiving device, as detailed in the previous claim, receives an OFDM signal where the first and second modulated symbols are transmitted within a *single* subcarrier. Thus, the receiver needs to separate the symbols that are multiplexed together on the same frequency channel within the OFDM signal.
7. A reception method comprising: receiving an OFDM modulation signal to which a first modulation symbol and a second modulation symbol are multiplexed, wherein the OFDM modulation signal comprises a plurality of subcarriers, the plurality of subcarriers include the first modulation symbol arranged in a first position in an in-phase quadrature-phase plane, and the second modulation symbol arranged in a third position in the in-phase quadrature-phase plane, the first modulation symbol is a symbol to which a first information signal is modulated using a first modulation scheme, the second modulation symbol is a symbol obtained by modulating a second information signal using the first modulation scheme, and by changing a second position at which a signal point of the second modulated information signal is arranged to the third position in the in-phase quadrature-phase plane; separating the first modulation symbol and the second modulation symbol included in the OFDM signal; demodulating the first information signal from the first modulation symbol; and demodulating the second information signal from the second modulation symbol.
A method for receiving data starts by receiving an OFDM signal comprised of several subcarriers, with a first symbol and a second symbol multiplexed together. The first symbol represents a first information signal modulated with a particular modulation scheme and is positioned at a certain location on the IQ plane. The second symbol is derived from a second modulated data signal (using the same scheme), but has its IQ plane position shifted to a different location. The method involves separating the two symbols, then demodulating the first data signal from the first symbol based on its position, and separately demodulating the second data signal from the second symbol using the shifted IQ plane location.
8. The reception apparatus according to claim 7 , wherein the first modulation symbol and the second modulation symbol are arranged in a same subcarrier in the received OFDM modulation signal.
The reception method mentioned in the prior claim involves receiving an OFDM signal where the first and second modulated symbols reside within a single subcarrier. As a result, the receiver must distinguish and separate the symbols that are combined on the same frequency channel within the OFDM signal.
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September 7, 2012
June 11, 2013
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